A Useful Overhang Gauge With Some "Ifs" Attached

Someone on one of the Facebook turntable groups asked what "overhang" was. None of the answers that I read properly defined it, (though a few talked about the head shell slots being involved) and I've forbidden myself from ever again participating on any of those groups after being called a "liar and a bullshit artist" in response to one innocent comment I made and "an industry puppet" following another.

One time someone asked what parameters were important for setting up a spherical stylus cartridge. I quite rightly answered "All you need concern yourself with is overhang, anti-skating and stylus pressure." The response was immediate: "How arrogant of you!" That was followed by the upset individual explaining that a friend's defective spherical stylus cartridge required more.

So yes, I'm finished "contributing" to Facebook. And in case you've never thought about it, consider that the spherical stylus is like a ball: no matter how you orient the "ball" neither the SRA nor the zenith angle change. This is one reason people like spherical stylus cartridges: it's almost impossible to screw up the installation. It's also almost impossible to get out of the groove all of the information the chisel-shaped cutting stylus inscribed into the groove!

So for those unsure, "overhang" literally refers to the distance from the center of the spindle to stylus tip as specified by the tone arm manufacturer. The pivot-to-spindle distance is the arm's actual length. Add the "overhang" and you get the arm's effective length. The reasons for producing a pivoted arm's arc beyond the spindle were defined by The Gramophone Magazine's Percy Wilson in the first half of the 20th century and can be skipped for the purposes of this discussion.

The only reason there are head shell slots in the first place is because no standard exists that defines the distance from the cartridge fixing screws to the stylus tip, so head shell slots allow for a wide variety of cartridges to be properly set up for "overhang".

Acoustand Audio in the U.K. has created a fairly easy to use "Overhang Gauge", model OHG-02. While the instructions claim "the Acoustand Overhang Gauge is all the tool you should ever need to get the job done within minutes", that is only true if your pivot to spindle distance is 100% accurate, since the gauge depends upon that accuracy to accurately do its job. If you measure and find it off by a few millimeters one way or the other, you can compensate on the gauge by adding or subtracting from the specified overhang.

So, if your turntable has a factory mounted arm (ie: Rega, Pro-Ject, VPI, etc.) you can be fairly certain the P2S distance is correct. The other issue you might face is does your arm's lateral travel allow it to extend directly over the spindle, which is a pre-requisite for using the Acoustand Overhang Gauge.

Assuming it does, using the device couldn't be easier, though the photos in the instruction manual are awful, especially if you are new at this! It may seem self-evident to the manufacturer that one needs to slide the ruler-like part of the gauge through the sliding pointer part, but it wasn't at first to me. Once you've assembled the device, you place it on the spindle, rotate the arm over directly over the spindle and lower the stylus onto the sliding part of the device. Your tonearm manufacturer should supply both the effective length and the actual length. Set the slider so its horizontal line matches the correct "overhang" specification (in millimeters) and then once you have the gauge in a straight line with the arm pivot, you turn the knurled screw to tighten the gauge onto the spindle. You can use the supplied "wedge" to disable platter rotation (if the distance between it and the plinth is within the wedge's range).

If the stylus tip does not land on the stylus tip circle, loosen the cartridge mounting screws and adjust until it does, then tighten the screws and if your stylus is spherical (and not defective), you are done! Otherwise you will need a protractor to adjust zenith angle.

If you have a two grid type paper alignment gauge where you have to go back and forth numerous times to set overhang, you'll find this gauge a real time saver, after which you can use that gauge to confirm zenith angle.

The Acoustand Audio Overhang Gauge is available in The United States for $85 from Robyatt Audio and in the U.K. from Acoustand Audio where you'll also find far better photos than are supplied with the gauge itself!

Tom L's picture

I know it comes in handy to keep in touch with friends and family, but otherwise Facebook is like an interface with Hell.

King Of Dirk's picture

“If you put 1,000,000 monkeys with typewriters in a room long enough, eventually you’ll get Hamlet.”

If nothing else, Facebook has proven this to be false - or at least provides some evidence that monkeys are smarter than Facebook users.

Anton D's picture

Are there any social media platforms you haven't been booted from yet! ;-P

I'm losing track!

Next thing we know, QAnon will be stalking you for promoting this new vinyl fetish that is threatening decent society.

Keep up the good work, sir.

Hey, look! Over there! A windmill! You better got tilt at it!

(All said with highest affection, I just can't help but chuckle when I see your passion collide with the wall of public stupidity.)

Michael Fremer's picture
That's why I wear a crash helmet at shows!

orthobiz's picture

The link works but I cannot find the gauge.


abelb1's picture

Thanks Michael,
I've actually been looking for something like this and I suspect it will also help me measure pivot to spindle distance with my callipers which don't quiet reach all the way (I've been using a piece of metal of known size to compensate as needed). One point isn't clear though which is do you set this device on the spindle horizontally or parallel to the line from pivot to spindle? Would it matter? And is this just done by eye? Sorry if it's an obvious question but I can't find the manual online. I ordered a silver one anyway which is all they had despite my concern that the markings on this version might not be legible. I suspect the lack of markings in the photos were just due the angle of light or flash though and I can report back when it arrives. Also as a long time (outside) observer of FB it seems to be becoming more broadly accepted that the platform rewards engagement over quality (and why shouldn't it considering its purpose), so don't be too frustrated with uninformed algorithmically emboldened know-it-all’s yelling over you. We can feel disheartened about the general state of affairs but that's another matter!

yeti's picture

How good a section of a sphere are these spherical styli? I’ve only set up one since I’ve had arms that could be adjusted and that was a Decca (London) Maroon wired for mono. I was expecting a horizontal arm would be as good as anything but there was a slight but audible change and an optimum with the arm a bit lower at the back than parallel if I varied it a bit around that and readjusted VTF each time (Naim Aro but with a Townshend paddle fitted). I’ve never seen a precision quoted for any stylus profile come to think of it.

cundare's picture

>overhang" literally refers to the distance from the center of the spindle to stylus tip as specified by the tone arm manufacturer. The pivot-to-spindle distance is the arm's actual length. Add the "overhang" and you get the arm's effective length.

Jeezus, Mikey, I certainly don't want to get in a pissing contest with you, and I KNOW that both of us fully understand the meaning of "overhang." But to somebody who does not, this definition is, um, a bit incomprehensible. The "distance from the spindle to the stylus" varies: Are you figuring the cartridge to be over the innermost groove, the outermost groove, or somewhere else?

I think you need to add words that specify that you're talkin gabout the distance from spindle to stylus when the arm-tube axis is positioned directly over the center of the spindle.

This may seem like nit-picking the obvious to guys like us, but not so much for a reader struggling to understand the geometry.

There's a good illustration at theanalogdept.com/overhang.htm

My 2c.

mobileholmes's picture

Do you mean to say that people don't understand the implications of a round tip? I imagine that gross zenith errors will affect the sound, but fairly large errors in zenith, azimuth and SRA are inaudible, mostly swamped by the gross harmonic distortion caused by a spherical stylus. I know most of you will think I'm a philistine for saying so, but there's no legitimate reason for using a spherical tip. That's why Expert Stylus will custom grind all manner of elliptical tips, including really large truncated ellipticals to find the undamaged areas in the groove of a 78. Are there cartridges that sound good with spherical tips? Yes, but that's in spite of using a spherical tip, not because of it. I asked Stan Ricker about the various cutting styli he'd seen over the years, and what he knew 2nd hand, and he couldn't think of any record where a spherical tip would improve performance. None! Do you think they cut with a round tip? Maybe the bottom of the cutting stylus is "round", but the overall shape of very old cutting styli were more like a garden spade, than a perfect sphere. Otherwise, the high frequencies would be severely limited. Of course, I have no idea what tip was used by Edison, but I don't play cylinders or historic recordings.

pafog825's picture

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